I like this idea; although, I'd prefer to have three levels:

RITUAL: A player could sign up for apprenticeship automatically, at the Academy or somewhere prominent in major hometowns. Some sort of "recruiter" NPC.

1) Apprenticeship: a period of indoctrination, not judgement. At this point an applicant may act inappropriately -- even switch cabals willy nilly -- but with rebuke, not rejection. This gives an RP outlet for those characters or players who want to express doubt or capriciousness without losing the game. At this point, the cabal is courting the applicant, not the other way around. It is the responsibility of the full cabal members to convince the applicant to live their lives a certain way.

RITUAL: Between apprenticeship and parole, the would-be cabal member pledges his loyalty to the cabal.

2) Parole: a period of judgement, in which the would-be member is tested and judged. Potentially some limited powers, mainly to test the applicant's use of them. Applicants would be roughly disciplined for inappropriate actions, and possibly booted for the worst improprieties.

RITUAL: Between parole and full membership, there would be the usual cabal interview, after which the successful member gives a formal oath of some kind.

3) Full membership with gradually increasing powers. Same as usual.

RITUAL: Leadership interviews. Some sort of public ceremony for newly appointed leaders. Not an oath or pledge this time, but a public speech.

Furthermore, I think Seantryn Modan must be destroyed.